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FIELD, LABORATORY AND NUMERICAL STUDY OF TRANSPORTATION EMISSIONS IN BUILT ENVIRONMENTS SURROUNDING MAJOR ARTERIALS IN SOUTHERN CALIFORNIAN CITIES

Marko Princevac
Department of Mechanical Engineering, University of California at Riverside, Riverside, California 92521, USA

Hansheng Pan
Department of Mechanical Engineering, University of California at Riverside, Riverside, California 92521, USA

Rufus Edwards
School of Social Ecology, University of California at Irvine, Irvine, California 92697, USA

Anahita Sfazl
School of Social Ecology, University of California at Irvine, Irvine, California 92697, USA

Marlon Boarnet
Department of Planning, Policy, and Design, University of California at Irvine, Irvine, California 92697, USA

Jun Wu
School of Social Ecology, University of California at Irvine, Irvine, California 92697, USA

Raul Lejano
Department of Planning, Policy, and Design, University of California at Irvine, Irvine, California 92697, USA

Sinopsis

Under the sponsorship of the University of California Transport Center, field measurements accompanied with laboratory experiments and numerical modeling were conducted for five southern Californian cities: Los Angeles, Long Beach, Huntington Beach, Anaheim and Pasadena. The goal of the study was to address transport of vehicle induced particulates in major urban arterials. Sites were selected to cover four typical urban settings: 1. Low density settlement; 2. Low-rise settlement; 3. Mid-rise settlement; 4. High-rise settlement. In addition, a relatively open area was also selected to serve as a base site. Mean wind, turbulence and virtual temperature were measured by a sonic anemometer at a sampling rate of 10Hz, particulate concentration (PM2.5) was measured with six DustTraks with a sampling rate of 1 Hz, and traffic counts are made by digital cameras. Three days measurements were performed in each area and three rush-hour periods for each day were covered.
The rapid decrease of the PM2.5 concentrations in the afternoon was observed in the field measurements. The lower concentrations in the afternoon are the consequence of stronger versical mixing, convective motions caused by high sensible heat flux, which resulted in efficient mixing and growth of the urban boundary layer. Concentrations were compared at leeward side of building and windward side of the building. The influence of building arrangement and meteorogical conditions on concentrations were revealed.
To conduct experiments under controlled conditions model cities were built for testing in the water channel. Transparent acrylic blocks were used as model buildings. The Particle Image Velocimetry (PIV) was used for flow measurements and the Planar Laser Induced Fluorescence (PLIF) was used for concentration measurements. The Quick Urban and Industrial Complex (QUIC) model was used to simulate flow and dispersion in all cites. The QUIC model performed well in complex urban setting with a slight over prediction of the near ground concentration.